# Airframe from non-aircraft grade material.

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#### stanislavz

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All is harder for highly stressed application.. But it is possible, as some acrobatic airplanes did show to us.

I think only one big no-no is fatigue concentration in ordinary aluminium. 2024 will hold up yo 500000 cycles of load higher than yield of 6060... But again - trusses are limited in buckling capacity.

#### Victor Bravo

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So let's get back to the method of using medium strength commercial (non-aerospace certified) aluminum 6061-T6 angle... and let's discuss the method of using "bent angles" instead of extrusions.

Using these angles to make a truss fuselage is not perfect, because obviously the angle has a lower buckling threshold than a tube.

BUT this is easily and reliably able to be calculated and quantified using very standard and accepted methods. The appropriate adjustment (to address the difference in buckling) can easily made to allow this. So (random example) instead of bending the L-angle from .025 aluminum sheet maybe it has to be .032 in certain places.

Being able to make an airplane fuselage out of less expensive non-aerospace material is a worthwhile goal, but it still needs to be consistent, predictable and reliable.

#### stanislavz

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Being able to make an airplane fuselage out of less expensive non-aerospace material is a worthwhile goal, but it still needs to be consistent, predictable and reliable.

But all this is simpler, after some truss computation digging.

Ie - tail section. 3 meters long, 1 high. Divided into 4 section by 3 bulkheads.. For low grade we divide it to 5 sections. And this will decrease our column height by 20%. And this would allow us for 56.25% of more stress on same section. But becuase our material is lower grade - we will stress it to lower level. But this will still left us some margin to save weight gaind due to extra bulkhead. At some extra work cost.

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#### AeroER

##### Well-Known Member

All is harder for highly stressed application.. But it is possible, as some acrobatic airplanes did show to us.

I think only one big no-no is fatigue concentration in ordinary aluminium. 2024 will hold up yo 500000 cycles of load higher than yield of 6060... But again - trusses are limited in buckling capacity.

Completely erroneous thinking. Fatigue occurs at low stress levels with lives dependent on the number of cycles, stress ratio, and stress concentration. (Those are fundamental first order factors.). Static strength and fatigue must be considered.

I wonder whether you have any understanding of sizing those gusseted joints.

I'm uncomfortable with your penchant for running programs that you don't understand, with applied loads that are wild guesses, and unknown constraints, but I doubt that matters in the end.

#### stanislavz

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I'm uncomfortable with your penchant for running programs that you don't understand, with applied loads that are wild guesses, and unknown constraints, but I doubt that matters in the end.
Ha ha i have used only pure algebra on that sizing thing. I did run some graphical solution of truses to have a base to play with.I know my loads. And i can preditcs loads from tube size and geometry of truss itself.

No touching of any gussets sizing or rivet numbers.

On fatigue limit - just some data which i do found. If could explain it better i would glad to hear it.

And yes - i did included Johnson parabola in my buckling calculator. No criplling factor yet. But it is related to wall thickness extremums...

#### stanislavz

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Ok...

So ~ 15 coffe later, and a lot of digging in net (and this forum), i was able to find, that aluminium tubing with gussets and pop-up rivets may lead to some really sturdy and nice construction.

Like this one for an exmple :

Or this one :

Sad, that company have gone out of bussines ? , and it is possible to se their web site only using web archive :

But it was dead simple to build and really fast build as a kit one. And was in a 1:1 situation then collided with ferris wheel.

#### Vigilant1

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There's a lot to like about the Morgans. They do seem simple to build, and the planes are reportedly sturdy. From a business standpoint, it may make good sense to have a few critical difficult-to-fabricate steel fittings within the main aluminum tube structure that you could sell (with serial numbers linked to plan set number). This helps out structurally to efficiently take point loads into the AL frame and also does (a little) as a disincentive to piracy.
The fabric portions of the Morgans do save weight, but I'm not sure if this would be popular with today's buyers. Probably okay for plans builders, but those opting for kits today may expect precut AL skins with predrilled rivet holes. With an underlying structure of AL tube (square or round), there are lots of options for closing it in.
I don't know why Morgan folded. I remember reading that customer support was problematic, but I'm not sure of that. They seemed to have little presence in the US.

Mark

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#### stanislavz

##### Well-Known Member
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Probably okay for plans builders, but those opting for kits today may expect precut AL skins with predrilled rivet holes. With an underlying structure of AL tube (square or round), there are lots of options for closing it in.
Ergh. I know the gay who now a gay who have basics dimension for this morgan like airplane. Because it a kr2 inspired one..

And using more info from HBA forum i was able to find dimension on used stock in truss (25x3 for longerons)... And that frame portion after pax could be made lighter, even in 25x1.5mm - 4.5kg saved here

+ Fuel tank top cover have to be a top deck why extra cover for it ? Not extra heavy panels just go to fully welded alum tank which is also a front top fuselage cover. Same in kr2 and in Ban-bi. ~ 3kg. Stock was build from 0.032", around 1.5m2 of alumnium. Or just go to wet wings.

And all that left - is around 6m2 of area to cover. Fabric here would weight 1-2kg with longerons and paint.

So - beeing lazy, we could cover all it with 1.2 mm alu-pp-alu composite with gsm of 1800. Slightly heavier than 0.5mm (0.025") alum, and lighter than 0.8mm (0.032") but it is so much sturdier and already painted. And it is fully to kiss aproach.

Will have to find thickness of turtle deck, it would bring total area to 9-10m2.

And go to lighter battery. 5kg saved more.

Our budget is 4.5 + 3 + 2 + 5 = 14.5 kg. To cover it with composite panel: 6 * 1.8 = 10.8 kg So we are on better weight, than we was before with fabric.

But - on same level, we might to cover turtle deck too. It looks to be build from heavier gauge, than 0.025", so if it is same as front deck - (0.032") - we are again saving some weight..

Tank like this one (this one from MCR01) :

And here are more than one good idea how to shed even more weight:

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#### stanislavz

##### Well-Known Member
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And one more places to think of - Morgan have specially welded structure to join two spars by full fuselage width overlap. Again - if done kr2 way as it was done before (central section of ~ 2-2.5m + two outer wing panels) - we are saving 2m of 50x50x6 alum profile, + shear web + shear wed doubler + that welded structure is no more. In 5-6 kg range at least.

And our outer wing panels can be build from smaller alum profile. But yes, they would add some connectors. Still - in lower stress region. Or even done in varie-easy way - just overlap. OR same as in morgan at the center. But- again with smaller gauge..

And yes, weight is the enemy, but putting bondo and sanding is also a no go.. + all extra paint job.

#### Vigilant1

##### Well-Known Member
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An off-the-shelf fuel tank would save quite a bit of hassle, maybe some money and maybe be less leak-prone than a welded aluminum one. I wonder if a molded crosslinked HDPE tank that would work is made anywhere? The Sonex tank is very sturdy, holds 16 US gal and goes under the glare shield. Over $400 with all fittings etc (and only available from them) so a more mass-market tank (boat, car racing, etc) would likely be more economical. #### stanislavz ##### Well-Known Member Supporting Member An off-the-shelf fuel tank would save quite a bit of hassle, maybe some money and maybe be less leak-prone than a welded aluminum one. I wonder if a molded crosslinked HDPE tank that would work is made anywhere? The Sonex tank is very sturdy, holds 16 US gal and goes under the glare shield. Over$400 with all fittings etc (and only available from them) so a more mass-market tank (boat, car racing, etc) would likely be more economical.
Yes and also no. Yes - if it is a safe non spilable tank. But you could buy that foam too.

But - 1mm of alum is easy to weld. And is dead safe go fuel. And on of my Friend weld them to order and he have weld a lot of them. Now we gave that ugly e10 added - it eats all old type of gas proof rubber and some epoxy. Before all was well. And rotax 912 carb are flooded after too long exposure to it.

Just here i still it is a good place to save some weight in total. Except - wet wings could save even more..

Btw - still no luck in finding suitable angle for longeron on this side of the pond.. 6060 is a no go for it.

#### stanislavz

##### Well-Known Member
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The fabric portions of the Morgans do save weight, but I'm not sure if this would be popular with today's buyers.
Btw. From my real life story, then i was building my house.

It is a pain in the a... To mix technology. Even if you are hiring others to do it. If started from concrete - do it from concretr to the roof. If done from wood - use ready made foundation etc..

Using ready composite paneles eliminates more than one technology. Always - painting with all preparation hassle, glue and saw of the fabric. Same tech as with gussets - cut, drill and rivet it down.

Or just rivet it if you have cnc'ed it before..

And - it does not dent as easily as 0.025' aluminium.

#### stanislavz

##### Well-Known Member
Supporting Member
Error in post 68. 0.5 mm is 0.02", and our composite panel with 1.2mm and 1800 gsm is similar to 0.025" alumiunium by 6.25% heavier. If we count not have to paint it we are in same position.

So this may be that black aluminium that is not alumiunium nor plywood. For fairings only of course in place of fabric...

#### Vigilant1

##### Well-Known Member
Supporting Member
Btw - still no luck in finding suitable angle for longeron on this side of the pond.. 6060 is a no go for it.
This is very strange. A wide variety of aluminum extrusions are available in the US, and it seems to be easy to get in Australia ("alloy" in the parlance of "down under", as though steel isn't also "alloy").

Surely aluminum extrusions on various alloys are needed and used in Europe, too?

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#### Victor Bravo

##### Well-Known Member
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Ergh. I know the gay who now a gay who have basics dimension for this morgan like airplane.

I know a few as well, but what does that have to do with anything?

BJC

#### stanislavz

##### Well-Known Member
Supporting Member
I know a few as well, but what does that have to do with anything?

Trying to find as many data as possible. Here for example ehere is tons of data on original kr2. KR Super2

#### raytol

##### Well-Known Member
Supporting Member
There's a lot to like about the Morgans. They do seem simple to build, and the planes are reportedly sturdy. From a business standpoint, it may make good sense to have a few critical difficult-to-fabricate steel fittings within the main aluminum tube structure that you could sell (with serial numbers linked to plan set number). This helps out structurally to efficiently take point loads into the AL frame and also does (a little) as a disincentive to piracy.
The fabric portions of the Morgans do save weight, but I'm not sure if this would be popular with today's buyers. Probably okay for plans builders, but those opting for kits today may expect precut AL skins with predrilled rivet holes. With an underlying structure of AL tube (square or round), there are lots of options for closing it in.
I don't know why Morgan folded. I remember reading that customer support was problematic, but I'm not sure of that. They seemed to have little presence in the US.

Mark
My company ( Wedgetail Aircraft) in Australia has the rights to all the Morgan aircraft. Good and rugged aircraft that is simple to build. I am changing to a welded steel safety frame forward of the seat backs. This will allow us to set all the wing angles, control column, canopy and firewall at the factory.
Like everything in aviation it is progressing slowly! All aluminium structure including the skins which are assembled using pop rivets. We do the solid rivetting on the wing spars, etc for you. Unfortunately, the price of the kits has had to increase so the interest has waned.

#### stanislavz

##### Well-Known Member
Supporting Member
My company ( Wedgetail Aircraft) in Australia has the rights to all the Morgan aircraft. Good and rugged aircraft that is simple to build. I am changing to a welded steel safety frame forward of the seat backs. This will allow us to set all the wing angles, control column, canopy and firewall at the factory.
Like everything in aviation it is progressing slowly! All aluminium structure including the skins which are assembled using pop rivets. We do the solid rivetting on the wing spars, etc for you. Unfortunately, the price of the kits has had to increase so the interest has waned.
Hello !

Are you willing to share more information on this new-new aircraft ? I was able to verify that cruise, but for example - empty weight is a gamble all the time. Tail section will have a truss undernetah ? Or sheet metal only ?

Sadly, that it is a no go for ul category here, in eu. But again, on bussines side you would have to compete with shiny composite boxes with 200-220 kg weight empty.

#### raytol

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Supporting Member
Hi Stanislavs,
All the Morgan aircraft are designed to be really strong and rugged. We are in design mode to increase the Gross weight of the Cougar and Sierra's. The trusses go from firewall to vertical tail rear spar. Sheet metal is not as sexy as composite but you can put it together in your garage without the smell going all through the house!

#### Geraldc

##### Well-Known Member
and let's discuss the method of using "bent angles" instead of extrusions.
If you are folding why not make top hat section with the outer skin completing the box?